1. Field of the Invention
The present invention relates to power conversion, and more specifically, the present invention relates to a circuit and method for driving FETs (field-effect transistors) in a saturating self-oscillating push-pull isolated DC-DC converter.
2. Description of the Related Art
Bipolar junction transistors (BJTs) have been used as driving switches in saturating self-oscillating push-pull isolated DC-DC converters. However, because BJTs are current-controlled devices, they generally exhibit larger switching losses than voltage-controlled devices, such as MOSFETs (metal-oxide-semiconductor field-effect transistors). These switching losses become a significant source of power loss in a saturating self-oscillating push-pull isolated DC-DC converter that is operated at relatively high switching frequencies.
Accordingly, when BJTs are used in a saturating self-oscillating push-pull isolated DC-DC converter, the transformer of the DC-DC converter must be designed with a high number of primary turns and/or a large cross-sectional core area to lower the switching frequency. Furthermore, BJTs typically have gains that vary widely with temperature, which can result in a number of problems, including difficulty during start-up at low operating temperatures.